import junit.framework.TestCase;
import org.junit.Test;
public calss StringBufferDemoText extend TestCase{
     StringBuffer str1 = new StringBuffer("StringBuffer");
     StringBuffer str2 = new StringBuffer("StringBufferStringBuffer");
     StringBuffer str3 = new StringBuffer("StringBufferStringBufferStringBuffer");

    @Test

    public void testcharAt() throws Exception{

        assertEquals('S',str1.charAt(0));

        assertEquals('g',str1.charAt(5));

        assertEquals('r',str1.charAt(11));

    }

    @Test

    public void testcapacity() throws Exception{

        assertEquals(28,str1.capacity());

        assertEquals(40,str2.capacity());

        assertEquals(52,str3.capacity());

    }

    @Test

    public void testlength() throws Exception{

        assertEquals(12,str1.length());

        assertEquals(24,str2.length());

        assertEquals(36,str3.length());

    }

    @Test

    public void testindexOf() throws Exception{

        assertEquals(0,str1.indexOf("Str"));

        assertEquals(5,str2.indexOf("gBu"));

        assertEquals(10,str3.indexOf("er"));

    }

}
